1. Field of the Invention
The present invention relates generally to circuit interrupters and more particularly to an operation counter for a load-current interrupting tool, commonly known as a loadbreak tool, that is utilized for opening medium and high-voltage circuit-isolating devices such as disconnecting fuses, disconnecting switches, cutouts, or the like.
2. Description of the Related Art
It is common practice in the electrical power distribution field to utilize a load-current interrupting tool, commonly known as a loadbreak tool, to open circuit-isolating devices such as disconnecting fuses, disconnecting switches, cutouts, or the like. In this manner, the circuit. isolating devices do not require load-interrupting capabilities. The loadbreak tool is carried on an insulating pole and manipulated by an operator via the pole. A load current interrupting tool of this type is the Loadbuster.sup.R Portable Loadbreak Tool available from the S&C Electric Company, Chicago, Ill. Reference may also be made to the following U.S. patents for a detailed description of a portable loadbreak tool of this general type: 2,816,978, 2,816,980, 2,816,985 and 5,650,602. A typical circuit-isolating device with which the portable loadbreak tool is utilized is illustrated in U.S. Pat. Nos. 4,414,527 and 5,502,427 and in the aforementioned U.S. Pat. No. 2,816,980. A circuit-isolating device of this type is the S&C Type XS Fuse Cutouts. When the cutout or other device, is connected in a circuit and is carrying a load current, the contacts of a movable portion (fuse tube) are in conductive engagement with respective upper and lower stationary terminals of the mounting.
The loadbreak tool includes two external, conductive attachment arrangements. A first of the conductive arrangements is arranged to selectively engage a hook-shaped anchor (commonly referred to as a Loadbuster.sup.R hook) carried by the mounting of the cutout and connected electrically to the upper stationary terminal of the mounting. The second conductive arrangement is a detachable latch member that is utilized to engage a pull ring or the like provided on the fuse tube of the cutout. The pull ring is electrically connected to the upper contact of the fuse tube. The loadbreak tool includes internal arc-interrupting facilities having separable arc-interrupting contacts which are in a closed position when the loadbreak tool is connected to the cutout. Each of the separable arc-interrupting contacts is connected to a respective one of the attachment arrangements.
The loadbreak tool provides for relative movement between the two attachment arrangements while also providing a conductive path between the stationary terminal of the mounting and the upper terminal of the fuse tube via the pull ring. When the operator pulls downward on the pole, the fuse tube pivots away from the cutout mounting and in the initial stages of opening the fuse tube, the load current path is maintained through the separable contacts of the loadbreak tool. After the continued opening of the fuse tube of the cutout has caused appropriate relative motion between the two attachment arrangements of the loadbreak tool, the arc-interrupting contacts are opened such that load interruption takes place internally of the loadbreak tool. Next, the loadbreak tool is detached from the cutout and removed from the vicinity of the cutout. A manually operable resetting latch arrangement is then manipulated by the operator to permit resetting of the loadbreak tool for subsequent use. The resetting of the loadbreak tool closes and resets the separable arc-interrupting contacts, returns the conductive attachment arrangements to their initial positions, and resets an internal trigger mechanism.
The operating life of the loadbreak tool depends upon the number of operations and the severity of the switching duties. Based on typical usage, involving an intermixture of varied switching duties, 500-1000 operations may normally be expected between required inspections. During such periodic inspections, various internal parts are inspected. Based on such inspection, reconditioning is accomplished as required including the replacement of various parts. Since the number of operations between typical inspections is large and there are no audible or visual signals that indicate the need for replacement of worn component parts, the number of operations should be accumulated and kept track of. However, since it is difficult to accurately keep track of the actual number of operations, the scheduling of maintenance is not always accurate, i.e. maintenance may be more frequent than typically required or may be unintentionally delayed until a problem is noticed.